In order to provide epoxy resin systems for reaction injection molding (RIM) applications, it is desirable that a favorable mix ratio between the epoxy resin and hardener be obtained. Such a favorable mix ratio, by weight, of epoxy resin to hardener is considered to be from about 1:1 to about 1.5:1. The usual amine hardeners such as, for example, ethylenediamine, diethylenetriamine, methylenediamine, hydrogenated methylenediamine, have amine hydrogen equivalent weights of from about 15 to about 53 which provide epoxy to hardener mix ratios of from about 3.4:1 to about 12:1.
In RIM epoxy systems, a considerable quantity of a trifunctional epoxy resin may be employed to provide a crosslinked network to the cured polymer. Since these trifunctional epoxides are usually solid resins, they must be heated before mixing with the hardener. It is therefore desirable that the viscosities of these epoxides and the curing agent or hardener be compatible at the mix temperature.
It has now been discovered that the compositions of the present invention provide more suitable mix ratios thereby lending them particularly suitable for epoxy RIM applications as well as conventional epoxy applications.